1k6o
From Proteopedia
Crystal Structure of a Ternary SAP-1/SRF/c-fos SRE DNA Complex
Structural highlights
Function[SRF_HUMAN] SRF is a transcription factor that binds to the serum response element (SRE), a short sequence of dyad symmetry located 300 bp to the 5' of the site of transcription initiation of some genes (such as FOS). Required for cardiac differentiation and maturation. [ELK4_HUMAN] Involved in both transcriptional activation and repression. Interaction with SIRT7 leads to recruitment and stabilization of SIRT7 at promoters, followed by deacetylation of histone H3 at 'Lys-18' (H3K18Ac) and subsequent transcription repression. Forms a ternary complex with the serum response factor (SRF). Requires DNA-bound SRF for ternary complex formation and makes extensive DNA contacts to the 5'side of SRF, but does not bind DNA autonomously. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCombinatorial DNA binding by proteins for promoter-specific gene activation is a common mode of DNA regulation in eukaryotic organisms, and occurs at the promoter of the c-fos proto-oncogene. The c-fos promoter contains a serum response element (SRE) that mediates ternary complex formation with the Ets proteins SAP-1 or Elk-1 and the MADS-box protein, serum response factor (SRF). Here, we report the crystal structure of a ternary SAP-1/SRF/c-fos SRE DNA complex containing the minimal DNA-binding domains of each protein. The structure of the complex reveals that the SAP-1 monomer and SRF dimer are bound on opposite faces of the DNA, and that the DNA recognition helix of SAP-1 makes direct contact with the DNA recognition helix of one of the two SRF subunits. These interactions facilitate an 82 degrees DNA bend around SRF and a modulation of protein-DNA contacts by each protein when compared to each of the binary DNA complexes. A comparison with a recently determined complex containing SRF, an idealized DNA site, and a SAP-1 fragment containing a SRF-interacting B-box region, shows a similar overall architecture but also shows important differences. Specifically, the comparison suggests that the B-box region of the Ets protein does not significantly influence DNA recognition by either of the proteins, and that the sequence of the DNA target effects the way in which the two proteins cooperate for DNA recognition. These studies have implications for how DNA-bound SRF may modulate the DNA-binding properties of other Ets proteins such as Elk-1, and for how other Ets proteins may modulate the DNA-binding properties of other DNA-bound accessory factors to facilitate promoter-specific transcriptional responses. Crystal structure of a ternary SAP-1/SRF/c-fos SRE DNA complex.,Mo Y, Ho W, Johnston K, Marmorstein R J Mol Biol. 2001 Nov 30;314(3):495-506. PMID:11846562[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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